Give one example of a molecule not obeying octet rule.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Octet Rule:**
The octet rule states that atoms are most stable when they have eight electrons in their valence shell. This is typically achieved through the formation of chemical bonds.

2. **Identifying a Molecule that Does Not Follow the Octet Rule:**
We need to find an example of a molecule where one or more atoms do not have eight electrons in their valence shell. A common example is phosphorus pentafluoride (PF5).

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